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PubMed2000

Case report of a pigmented dentigerous cyst and a review of the literature on pigmented odontogenic cysts.

This paper reports the first case of a dentigerous cyst containing melanin-pigment and melanocytes in the lining epithelium, and the first case of a odontogenic cyst with macroscopically visible pigmentation in the cyst wall. The patient was a 29-year-old Japanese male with a cystic lesion in the left retromolar area of the mandible. Pathologic examination revealed the lesion to be a dentigerous cyst with or without mild surface keratinization, and numerous granules of melanin-pigment were distributed in the basal cells of the epithelial lining. Furthermore, dendritic melanocytes were scattered in the basal layer. Review of the literature revealed that pigmented odontogenic cysts are uncommon, and only 11 cases have been documented; eight were odontogenic keratocyst, one was a gingival cyst, one was a botryoid odontogenic cyst, and one was a lateral periodontal cyst. The possible origin of melanocytes in odontogenic lesions is discussed.

Adult↗
PubMed1980

The effect of actinomycin D on the nucleolus and on pigment synthesis in pigment cells of Xenopus laevis: an ultrastructural study.

The effect of AMD on the nucleolus and on melanogenesis in differentiating pigment cells of Xenopus laevis was investigated in cultured neural crest cells. Cultures were treated with either 2 or 10 microgram/ml AMD for 41/2 hours. Following treatment the antibiotic was removed. Observations of the cells were made with both scanning and transmission electron microscopes. Actinomycin D almost entirely stopped pigment formation in neural crest cultures during treatment. The morphological sequence in the formation of melanin granules in the untreated pigment cells appears to be as follows: The earliest identifiable premelanosome is membrane-bound and contains very thin laminae and/or small vesciles. The premelanosomes become until they are approximately the size of mature melanin granules and there is thickening of the laminae, which appear to have a periodic substructure. The cells eventually become packed with electron-dense melanin granules. Compared with controls, the cytoplasm of treated cells showed a greater abundance of smooth- than of fuzzy-membraned vesicles, less rough endoplasmic reticulum, dilatation of the Golgi cisternae, and a smaller number of premelanosomes. The necleolus showed segregation and blebbing of its components, decrease in size and even disappearance; sometimes confluence of the components occurred. The most consistent morphological effect of AMD on the nucleolus was the separation of the fibrillar and granular areas. The granular component appeared to undergo marked changes in size and arrangement and is thought to be the source of ribosomal RNA precursors. The alteration in size of the outer component of the nucleolus went hand in hand with disappearance of free ribosomes from the cytoplasm of treated cells and inhibition of pigment synthesis.

Animals↗
PubMed1981

Cone pigments in acute posterior multifocal placoid pigment epitheliopathy.

We measured cone pigment density and kinetics with a reflection retinal densitometer during the evolution and resolution of posterior pole lesions in a 17-year-old patient with acute posterior multifocal placoid pigment epitheliopathy. Three weeks after onset, density was markedly reduced and regeneration complex and nonexponential. Pigment density increased, and kinetics returned to normal as the disease resolved.

Acute Disease↗
PubMed1987

Cell patterning in pigment-chimeric eyes in Xenopus: germinal transplants and their contributions to growth of the pigmented retinal epithelium.

We have examined the process by which small groups of pigmented germinal cells transplanted orthotopically from stage 30-38 donor embryos into stage 28-38 albino hosts contribute new postmitotic cells to the pigmented retinal epithelium of the growing larval eye in Xenopus. In the great majority of chimeric eyes, the transplant healed to occupy a small arc-territory at the intended dorsal or anterior position on the host germinal zone. Over the course of subsequent weeks, the transplanted germinal cells added new mitotically quiescent cells to the distal rim of the pigmented retinal epithelium and so gave rise to an elongating black sector on the growing larval eye. Cellular details at the boundaries of the graft-derived sector were stable over time; the accumulation of such landmarks provided a summary record--in the proximodistal axis of the older eye--of the growth history of the transplant. Case-to-case variation among both groups of transplants suggested a measure of indeterminancy in the details of germinal cell growth.

Animals↗
PubMed2000

Influence of pigment content, intracellular calcium and cyclic AMP on the ability of human retinal pigment epithelial cells to contract collagen gels.

PURPOSE: The aim of the study was to determine to what extent collagen gel contraction could be reduced by calcium and calmodulin antagonists and agents that elevate cyclic AMP in order to develop a pharmacological approach to prevent/arrest RPE contraction of epiretinal membranes in proliferative vitreoretinopathy. We also explored a possible role of pigment in collagen gel contraction. METHOD: We measured RPE mediated contraction of 3D collagen gels in the presence and absence of the calcium and calmodulin antagonists TMB8, Verapamil and Tamoxifen and the cAMP elevating agents IBMX and Forskolin. The effect of pigment on collagen gel contraction was assessed by comparing gel contraction mediated by RPE cells re-pigmented with melanin with that mediated by unpigmented RPE. The effect of IBMX on RPE proliferation was assessed using a BrdU ELISA and the effects of IBMX on RPE cytoskeleton and cell shape were assessed using Actin and Cytokeratin immunocytochemistry. RESULTS: We report that both cAMP elevating agents and calcium and calmodulin antagonists reduce RPE mediated collagen gel contraction. Cyclic AMP elevation was more effective than a reduction in calcium in reducing contraction. There were no significant advantages in combining both approaches. The presence of melanin had no effect on gel contraction. Calcium antagonists and particularly agents which elevate cAMP caused RPE cells in collagen gels to extend fewer and shorter processes. cAMP elevation in particular caused RPE cells to become more rounded and develop arborized cell processes. Immunostaining for actin and cytokeratin revealed changes in cytoskeletal organisation in response to IBMX in that cells contained less actin than untreated cells and concentrated cytokeratins more centrally. CONCLUSION: We have identified two possible pharmacological approaches which may provide a new direction for preventing or slowing down the development of PVR.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Two pigmented lesions of the female genital system. Blue nevus of the uterine endocervix and melanin pigmentation of the vagina.

Five cases of benign pigmented lesions in unusual sites are reported. They consist of four blue nevi of the uterine endocervix, respectively the 38th, 39th, 40th and 41st cases according to our review of the literature, and one melanin pigmentation of the vagina, the 12th case according to our review of the literature. The theories about the presence of melanin-containing cells (melanocytes) in unusual sites are reported and the singular finding of melanin pigmentation observed in vaginal epithelium is discussed.

Epithelium↗
PubMed1994

Na(+-) Cl(-)- and HCO3(-)-dependent base uptake in the ciliary body pigment pigment epithelium.

Segments of whole ciliary body dissected from Dutch belted rabbits were incubated for 60 min at 36 degrees C in a 30 microM Ca2+ Ringer's. The inner limiting membrane with its adherent non-pigmented epithelium then was mechanically removed from the surface. The newly-exposed viable layer of pigmented cells was then loaded with the fluorescent probe 2'-7'-bis (carboxymethyl)-5(6) carboxyfluorescein by incubating the segments for 45 min at RT with the cell permeable acetoxymethoxy form of the dye. These loaded tissues were perfused in a flow-through chamber, mounted on the heated stage of a microscope equipped for quantitative epifluorescence, and the intracellular pH (pHi) of small groups of cells was derived from the ratio of emission intensities generated by excitations at 490 and 440 nm, respectively. In N[2-hydroxyethyl] piperazine-N"-[2 ethane sulfonic acid](Hepes)-buffered Ringer's the intracellular pH was 7.23 +/- 0.21 (+/- S.D., n = 20). Replacement of 28 mM Hepes by 28 mM HCO3-/5% CO2 led to a 0.14 +/- 0.04 increase in pHi. This increase required the presence of Na+ and Cl- and was inhibited by 0.2 mM diisothiocyanatostilbene-2-2'-disulfonic acid. These observations as well as characteristic pHi, responses to the removal or introduction of Na+ or Cl- indicated the presence in the pigmented cells of a Na(+)- and Cl(-)-dependent HCO3- transporter responsible for base uptake.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1975

Melanogenesis in the pigment epithelium of chicken embryos. I. Topogenesis of pigment in the iris anlage.

The iris anlage of 2-10 and 15 days old chicken embryos were studied histochemically, and by both light and electron microscopy. Light microscopic serial sections showed that pigmentation began at the outer layer of the posterior eye pole and progressed from there forwards to the optic cup margin. The entire outer layer of the optic cup as well as the pupillary margin were completely pigmented by the 4th day of incubation. By the 10th day the posterior iris epithelium was totally pigmented. Electron microscopical studies showed that the first premelanosomes appeared at about the 3rd day of incubation in the anterior iris anlage with the exception of the pupillary margin. It could be shown that melanogenesis progressed through the following steps: premelanosomes, followed by tyrosinase activity in a Golgi-associated system of smooth endoplasmic reticulum (GERL) and small vesicles and finally differentiation of the melanosomes. The possible origin of the premelanosomes and the formation of melanin are discussed.

Animals↗
PubMed2003

[Nd-YAG laser iridotomy in pigment dispersion syndrome and pigment dispersion glaucoma].

Pigment dispersion syndrome is characterized by iris transillumination defects, Krukenberg spindels, and dense trabecular pigmentation. Additional features are bilaterality, myopia, concavity of the peripheral iris, a higher incidence in men than in woman,and young age of onset. A mechanism of reverse pupillary block causes iridozonular friction. Laser iridotomy is recommended as treatment to prevent further pigment dispersion and pigmentary glaucoma.

Accommodation, Ocular↗
PubMed1986

Pigment cell pattern formation in Taricha torosa: the role of the extracellular matrix in controlling pigment cell migration and differentiation.

The neural crest is a population of highly migratory mesenchymal cells that ultimately localize in specific sites and differentiate into a variety of cell types. This report describes studies on the factors governing the migratory pathways, differentiation, and ultimate localization of the neural crest-derived pigment cells (black melanophores and yellow xanthophores) in the California newt, Taricha torosa. Melanophores first appear scattered in the dorsal portion of the lateral neural crest migratory pathway (between the somites and the ectoderm). These cells are eventually found in two stripes: a dorsal stripe that runs along the apex of the somites, and a midbody stripe near the somite-lateral plate mesoderm border. Melanophores are not seen in the dorsal fin of prehatching embryos. Xanthophores can be identified with the light microscope using NH4OH-induced autofluorescence of pteridines and in the transmission electron microscope (TEM) by the presence of pterinosomes. Xanthophores first appear scattered among the melanophores over the surface of the somites; these cells eventually are found between the two melanophore stripes and in the dorsal fin. We were interested in determining the roles of the extracellular matrix (ECM) in controlling the formation of pigment cell patterns in T. torosa. Immunocytochemistry, Alcian blue staining of paraffin sections and ruthenium red staining of thin sections (accompanied by Streptomyces hyaluronidase and chondroitinase ABC digestion) were used to identify the composition and distribution of the ECM surrounding the pigment cells at various stages during development. The adhesive glycoprotein fibronectin is found in the dorsal portion of the lateral neural crest migratory pathway as well as in the dorsal fin matrix. Glycosaminoglycans (GAG) are found primarily in the dorsal fin and in the ECM surrounding the notochord. The dorsal fin ECM contains hyaluronate (HA), which was identified in the TEM as Streptomyces hyaluronidase-sensitive 3-5 nm microfibrils, as well as sulfated proteoglycan aggregates. We then confronted T. torosa neural crest cells in vitro with known ECM molecules. When neural folds are explanted onto tissue culture plastic in half-strength L-15 medium containing 10% fetal calf serum (FCS), cells migrate from the explant and differentiate into melanophores after 6 to 9 days. Xanthophores appear in the cultures 2 to 4 days after the appearance of melanophores. When cultured on three-dimensional collagen gels, xanthophores migrate significantly farther (P less than 0.01) onto and into the collagen than melanophores (336 +/- 183 vs 196 +/- 160 microns from the edge of the explant).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Bovine non-pigmented and pigmented ciliary epithelial cells in culture: comparison of catalase, superoxide dismutase and glutathione peroxidase activities.

Non-pigmented epithelial (NPE) cells and pigmented epithelial (PE) cells were dissociated from bovine ciliary processes by brief digestion with pronase and grown in a culture medium containing high fetal bovine serum for at least 25 generations. Both types of cells grown to confluence showed the presence of intermediate junctions with associated tonofilaments. PE cells were distinguished from NPE cells by pigmentation during the early passages. Gamma-glutamyl transpeptidase activity was associated almost exclusively with NPE cells and proved to be a useful enzymatic marker to distinguish NPE from PE. A comparison was made between NPE and PE cells as to the levels of enzymes involved in the detoxification of active oxygen species. Catalase, Se-dependent glutathione peroxidase and superoxide dismutase activities were significantly higher in NPE than in PE cells. The results suggest that NPE cells play the major role in detoxification of active oxygen species during aqueous humor formation.

Animals↗
PubMed1984

Peripheral retinal detachments and retinal pigment epithelial atrophic tracts secondary to central serous pigment epitheliopathy.

Twenty-five patients with central serous pigment epitheliopathy (CSP), also known as central serous chorioretinopathy, have been observed to have inferior hemispheric retinal pigment epithelial atrophic tracts, presumptive of antecedent retinal detachments. Five of these patients were noted to have clinically discernible, dependent peripheral retinal detachments. The clinical and fluorescein angiographic features of these patients are reviewed. Alterations in the retina, the retinal pigment epithelium (RPE) and the choroid are also described. They include the commonly associated manifestations of CSP such as RPE leaks and macular detachment as well as some newly recognized disturbances such as retinal capillary dilatation (telangiectasia), retinal capillary leakage, retinal lipid deposition, cystoid macular edema, choriocapillaris atrophy, choroidal neovascularization and disciform scarring.

Adult↗
PubMed1990

Retinal pigment epithelial folds associated with retinal pigment epithelial detachment in macular degeneration.

The authors reviewed six eyes that had a shallow retinal pigment epithelial detachment with the retinal pigment epithelium (RPE) thrown into folds. A contraction of subpigment epithelial fibrovascular tissue causes a folding of the overlying, intimately adherent RPE. Retinal pigment epithelial folds are a sign of subretinal neovascularization and are another manifestation of age-related macular degeneration.

Aged↗
PubMed2002

Variation in visual acuity within pigmented, and between pigmented and albino rat strains.

Many researchers assume that laboratory rats have poor vision, and accordingly, that they need not consider differences in the visual function of rats as a consequence of strain or experience. Currently, it is not specifically known whether rat domestication has negatively affected the visual function of laboratory rat strains, what the effects of strain albinism are on rat visual function, or whether there are strain differences in the visual function of laboratory rats that are independent of pigmentation. In order to address these questions, we measured psychophysically the vertical grating acuity of three pigmented (Dark Agouti, Fisher-Norway, Long-Evans) and three albino (Fisher-344, Sprague-Dawley, Wistar) strains of laboratory rats, and compared their acuity with that of wild rats. The grating thresholds of Dark Agouti, Long-Evans and wild strains clustered around 1.0 cycle/degree (c/d) and did not significantly differ from one another. Fisher-Norway rats, however, had a significantly higher threshold of 1.5 c/d. The grating thresholds of Fisher-344, Sprague-Dawley, and Wistar strains, which were clustered around 0.5 c/d, were significantly lower than those of the pigmented strains. These data demonstrate that there is significant strain variability in the visual function of laboratory rats. Domestication of Long-Evans and Dark Agouti strains does not appear to have compromised visual acuity, but in the case of Fisher-Norway rats, selective breeding may have enhanced their acuity. Strain selection associated with albinism, however, appears to have consistently impaired visual acuity. Therefore, a consideration of strain differences in visual function should accompany the selection of a rat model for behavioral tasks that involve vision, or when comparing visuo-behavioral measurements across rat strains.

Albinism↗
PubMed2006

Identification of two novel pigment precursors and a reddish-purple pigment involved in the blue-green discoloration of onion and garlic.

By using a model reaction system representing blue-green discoloration that occurs when purees of onion (Allium cepa L.) and garlic (Allium sativum L.) are mixed, we isolated two pigment precursors (PPs) and a reddish-purple pigment (PUR-1) and determined their chemical structures. PPs were isolated from a heat-treated solution containing color developer (CD) and either l-valine or l-alanine, and their structures were determined as 2-(3,4-dimethylpyrrolyl)-3-methylbutanoic acid (PP-Val), and 2-(3,4-dimethyl-1H-pyrrolyl) propanoic acid (PP-Ala), respectively. Next, PUR-1 was isolated from a heat-treated solution containing PP-Val and allicin, and its structure was determined as (1E)-1-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-yl)-prop-1-enylene-3-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-ylidenium). The structure of PUR-1 suggested that PP molecules containing a 3,4-dimethyl pyrrole ring had been cross-linked by an allyl group of allicin to form conjugated pigments. While PUR-1 is a dipyrrole compound exhibiting a reddish-purple color, a color shift toward blue to green can be expected as the cross-linking reaction continues to form, for example, tri- or tetrapyrrole compounds.

Butyrates↗